Rf module

ABSTRACT

The present invention provides an RF module capable of outputting balanced electromagnetic waves without requiring adjustment and easily realizing miniaturization. The RF module includes: a waveguide ( 3 ) having an area which is surrounded by a pair of ground electrodes ( 6 ) and ( 7 ) provided so as to face each other and through holes ( 8 ) for making electric conduction between the pair of ground electrodes ( 6 ) and ( 7 ) and in which electromagnetic waves in the TE mode can propagate and a one-wavelength resonator ( 11 ) is formed; and a pair of output lines ( 4   a ) and ( 4   b ) connected to portions corresponding to half-wavelength resonance regions (A) and (B) of the one-wavelength resonator ( 11 ) in the ground electrode ( 6 ).

TECHNICAL FIELD

The present invention relates to an RF module used for propagation ofelectromagnetic waves (RF signal) such as microwaves and millimeterwaves.

BACKGROUND ART

In association with improvement in a mobile communication technique orthe like, the frequency band of waves used for communication is beingspread to a high-frequency area such as a GHz band and communicationdevices used for communication are also being miniaturized. RF modulessuch as a waveguide and a filter used in communication devices of thiskind are also being requested to realize higher frequencies and furtherminiaturization. A waveguide line as disclosed in Japanese PatentLaid-open No. Hei 6-53711 and a filter using such a waveguide line asdisclosed in Japanese Patent Laid-open No. Hei 11-284409 have beendeveloped. As connection structures for connecting an RF module of thiskind, connection structures as disclosed in Japanese Patent Laid-openNos. 2000-216605 and 2003-110307 have been developed.

In this case, the waveguide line disclosed in Japanese Patent Laid-openNo. Hei 6-53711 includes, as shown in FIG. 1 in the publication, adielectric substrate (1) having conductor layers (2 and 3) and aplurality of conduction holes (4) which connect between the conductorlayers (2 and 3) and are disposed in two lines. The waveguide line isconstructed by a pseudo rectangular waveguide in which a region in theconductor is used as a line for transmitting a signal by surrounding alldirections of a dielectric material with the pair of conductor layers (2and 3) and pseudo conductive walls formed by the plurality of conductionholes (4). In this case, a waveguide line having such a configuration isalso called a dielectric waveguide line.

The filter disclosed in Japanese Patent Laid-open No. Hei 11-284409 isconstructed by, as shown in FIG. 1 in the publication, disposing aplurality of through conductors (26) forming an inductive window(coupling window) so as to establish electric connection (conduction)between a pair of main conductor layers (22 and 23) in a dielectricwaveguide line (25) as a pseudo rectangular waveguide constructed by adielectric substrate (21), the pair of main conductor layers (22 and 23)and a through conductor group (24) for sidewalls in a similar manner tothe waveguide line disclosed in Japanese Patent Laid-open No. Hei6-53711. Since the filter can be formed inside the dielectric substratesuch as a wiring board, the filter can be easily miniaturized.

In a connection structure between a dielectric waveguide line (pseudorectangular waveguide) and a line conductor (microstrip line) disclosedin the Japanese Patent Laid-open No. 2000-216605, as shown in FIG. 1 inthe publication, an end of a line conductor (20) is inserted into anopen end of a dielectric waveguide line (16), and the end and one mainconductor layer (12) are electrically connected to each other via a lineconductor (18) for connection and a through conductor (17) forconnection so as to form steps. The connection structure is a so-calledridge waveguide structure in which the interval between the pair of mainconductor layers (12 and 13) is narrowed. Therefore, at the time ofpropagation of RF signals (electromagnetic waves) from the lineconductor (20) to the dielectric waveguide line (16), electromagneticwaves propagating in the TEM mode through the line conductor (20) aremode-converted into electromagnetic waves propagating in a TE mode (TE₁₀mode) through the dielectric waveguide line (16).

On the other hand, in a connection structure between the waveguide line(in this example, the waveguide line is a component of a dielectricwaveguide filter) and a line conductor (microstrip line) disclosed inthe Japanese Patent Laid-open No. 2003-110307, as shown in FIG. 1 in thepublication, protruding portions (17 a and 17 b) are formed on theoutside of dielectric waveguide resonators (11 a and 11 d) forming adielectric waveguide filter, and conductive strip lines (15 a and 15 b)extending from the bottom surfaces of the dielectric waveguideresonators (11 a and 11 b) to the protruding portions (17 a and 17 b)and serving as input and output electrodes are formed. The conductivestrip lines (15 a, 15 b) are connected to conductive patterns (19 a and19 b) as line conductors formed on a wiring board (18). In theconnection structure, the conductive patterns (19 a and 19 b) areterminated on the bottom surfaces of the dielectric waveguide resonators(11 a and 11 d)-via the conductive strip lines (15 a and 15 b) formed soas to have the same width as that of the conductor patterns (19 a and 19b). Thus, to the bottom surfaces of the dielectric waveguide resonators(11 a and 11 d), input and output signals in the TEM mode are suppliedvia the conductive patterns (19 a and 19 b), respectively. Therefore,magnetic fields generated in the dielectric waveguide resonators (11 aand 11 d) by the input and output signals are coupled to magnetic fieldsin a fundamental resonance mode (TE mode (TE₁₀ mode)) of the dielectricwaveguide resonators (11 a and 11 d). As a result, electromagnetic wavespropagating in the TEM mode in the conductive patterns (19 a and 19 b)are mode-converted into electromagnetic waves propagating in the TE mode(TE₁₀ mode) in the dielectric waveguide resonators (11 a and 11 d) asdielectric waveguide lines. Electromagnetic waves propagating in the TEmode (TE₁₀ mode) in the dielectric waveguide resonators (11 a and 11 d)are mode-converted into electromagnetic waves propagating in the TEMmode in the conductive patterns (19 a and 19 b).

Incidentally, for example, as disclosed in the Japanese Patent Laid-openNos. 2000-216605 and 2003-110307, although most of RF modules currentlyproposed are to output electromagnetic waves in the TEM mode from thedielectric waveguide line (waveguide) as unbalanced electromagneticwaves, there is also a demand for realizing an RF module which outputsbalanced RF signals in the TEM mode from a waveguide (unbalanced tobalanced converter, so-called balun). To address the demand, forexample, an RF module (dielectric filter) as disclosed in JapanesePatent Publication No. 3351351 has been proposed. In the dielectricfilter, as shown in FIG. 1 in the publication, on an outer surface of adielectric block (1), external terminal (8) continued from one end of anexternal coupling line (25) and an external terminal (6) generatingcapacitance in cooperation with a resonance line (5 a) are formed,thereby constructing an unbalanced to balanced conversion circuit. Thephase difference between one of output signals output from the externalterminal (6) by the capacitive coupling and the other output signalsoutput from the external terminal (8) by the inductive coupling is setto 180 degrees by adjusting a capacitance value and an inductance valueof the coupled portions.

However, the unbalanced to balanced conversion circuit disclosed in theJapanese Patent Publication No. 3351351 has the following problems. Inthe unbalanced to balanced conversion circuit, in order to set the phasedifference between the two output signals to 180 degrees, thecapacitance value of the capacitive coupling and the inductance value ofthe inductive coupling have to be adjusted. Therefore, the unbalanced tobalanced conversion circuit has the problems such that it requires sometime and effort for the adjustment work and it is difficult tominiaturize the circuit since a signal path which is not operated as aresonator has to be provided in addition to a resonator.

DISCLOSURE OF INVENTION

The present invention has been achieved in consideration of suchproblems, and a main object of the invention is to provide an RF modulecapable of outputting balanced electromagnetic waves without requiringadjustment and, further, easily realizing miniaturization.

The RF module according to the invention to achieve the object includes:a waveguide having an area which is surrounded by a pair of groundelectrodes and a conductor for making electrical connection between thepair of ground electrodes, the pair of ground electrode being providedso as to face each other, and in which electromagnetic waves in the TEmode can propagate and a one-wavelength resonator is formed; and a pairof output lines connected to portions corresponding to half-wavelengthresonance regions of the one-wavelength resonator in one of the pair ofground electrodes.

In this case, preferably, the pair of output lines is formed so thatelectromagnetic waves in the TEM mode can propagate.

Preferably, the RF module further includes: a half-wavelength resonatorformed inside the waveguide and coupled to the one-wavelength resonator;and an input line which is connected to a portion corresponding to thehalf-wavelength resonator in one of the pair of ground electrodes andthrough which electromagnetic waves in the TEM can be input aselectromagnetic waves in the TE mode to the half-wavelength resonator.The half-wavelength resonator and the one-wavelength resonator can becoupled to each other via a waveguide or the like or directly.

In this case, it is preferable that the half-wavelength resonator andthe one-wavelength resonator be coupled to each other via a couplingwindow.

Preferably, the RF module further includes at least one anotherresonator which is formed between the half-wavelength resonator and theone-wavelength resonator and coupled to both of the resonators via acoupling window.

Preferably, the RF module further includes: another one-wavelengthresonator formed inside the waveguide and coupled to the one-wavelengthresonator; and a pair of input lines which are connected to portionscorresponding to half-wavelength resonance regions of the anotherone-wavelength resonator in one of the pair of ground electrodes andthrough which electromagnetic waves in the TEM mode can be input aselectromagnetic waves in the TE mode to the another one-wavelengthresonator. The another one-wavelength resonator and the one-wavelengthresonator can be coupled to each other via a waveguide or the like ordirectly.

In this case, it is preferable that the another one-wavelength resonatorand the one-wavelength resonator are coupled to each other via acoupling window.

Preferably, the RF module further includes at least one resonator formedbetween the another one-wavelength resonator and the one-wavelengthresonator and coupled to both of the resonators via a coupling window.

The input line can be any one of a strip line, a microstrip line, and acoplanar line.

Further, the output line can be any one of a strip line, a microstripline, and a coplanar line.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view showing the configuration of an RF module 1according to an embodiment.

FIG. 2 is a plan view of the RF module 1.

FIG. 3 is an explanatory drawing showing the magnetic field distributionof a magnetic field H1 around a connection part to a waveguide 3 in aninput line 2 of the RF module 1.

FIG. 4 is an explanatory drawing showing the magnetic field distributionof a magnetic field H2 around a connection part to the input line 2 inthe waveguide 3 of the RF module 1.

FIG. 5 is an explanatory drawing showing the magnetic field distribution(coupling state) of the magnetic fields H1 and H2 in the connectionparts to the input line 2 and the waveguide 3, respectively, in the RFmodule 1.

FIG. 6 is a characteristic diagram showing the relation between thefrequency and the phase difference in the RF module 1.

FIG. 7 is an explanatory drawing showing the intensity distribution of amagnetic field H3 around a connection part to an output line 4 a in thewaveguide 3 in the RF module 1.

FIG. 8 is a characteristic diagram showing the relation between thefrequency and the attenuation rate in the RF module 1.

FIG. 9 is a perspective view showing the configuration of an RF module21 according to the embodiment of the invention.

FIG. 10 is a perspective view showing the configuration of an input line32 and a connection part between the input line 32 and the waveguide 33in the RF module 31 according to the embodiment of the invention.

FIG. 11 is an explanatory drawing showing the magnetic fielddistribution (coupling state) of the input line 32 and the waveguide 33in the RF module 31.

FIG. 12 is a schematic diagram showing the configuration of an RF module41 according to the embodiment of the invention.

FIG. 13 is a schematic diagram showing the configuration of an RF module1A according to the embodiment of the invention.

FIG. 14 is a schematic diagram showing the configuration of an RF module41A according to the embodiment of the invention.

BEST MODE FOR CARRYING OUT THE INVENTION

A preferable embodiment of an RF module according to the invention willbe described hereinbelow with reference to the attached drawings.

First, the configuration of the RF module according to the inventionwill be described with reference to the drawings.

As shown in FIG. 1, an RF module 1 includes an input line 2 throughwhich electromagnetic waves in the TEM mode propagate, a waveguide 3which is coupled to the input line 2 and through which electromagneticwaves in the TE mode (concretely, TE₁₀ mode of the lowest order)propagate, and a pair of output lines 4 a and 4 b which are coupled tothe waveguide 3 and through which electromagnetic waves in the TEM modepropagate. In this case, the waveguide 3 forms a dielectric waveguide(dielectric waveguide line) by including a pair of ground electrodes 6and 7 disposed to face each other while sandwiching a dielectricsubstrate 5, and a plurality of through holes 8 penetrating thedielectric substrate 5 to make electric conduction between the pair ofground electrodes 6 and 7, thereby functioning as a conductor in theinvention. The through holes 8, whose inner face is metallized, aredisposed at intervals each equal to or less than a predetermined width(for example, a width of one fourth of the guide signal wavelength) inorder to prevent leakage of the electromagnetic waves propagating thewaveguide 3. With this configuration, the waveguide 3 enables theelectromagnetic waves to propagate, for example, in an S direction inthe diagram without leaking in an area surrounded by the pair of groundelectrodes 6 and 7, and the through holes 8. The waveguide 3 can be adielectric waveguide filled with dielectric as in the embodiment or,although not shown, a cavity waveguide whose inside is cavity. In FIG.1, the uppermost layer is hatched and is shown with thickness omitted.

As shown in FIG. 1, in the waveguide 3, a plurality of other throughholes 9 for making electrical conduction between the pair of groundelectrodes 6 and 7 are provided in a line by penetrating the dielectricsubstrate 5. In this case, the through holes 9 are formed in the samestructure as that of the through holes 8 described above. Therefore, asshown in FIGS. 1 and 2, in the waveguide 3, coupling windows 12 areformed in spaces between the through holes 9 and the through holes 8. Ahalf-wavelength resonator 10 is formed on the input side of thewaveguide 3 and a one-wavelength resonator 11 is formed on the outputside. The half-wavelength resonator 10 is magnetically coupled to ahalf-wavelength resonance region A out of the half-wavelength resonanceregions A and B in the one-wavelength resonator 11 via the couplingwindows 12. Therefore, the RF module 1 is constructed so as to functionas a filter (concretely, a bandpass filter). As an example, thewaveguide 3 is constructed by disposing the half-wavelength resonator 10and the one-wavelength resonator 11 so that the general shape in planview becomes an L shape. Alternately, the waveguide 3 may be constructedby disposing the half-wavelength resonator 10, the half-wavelengthresonance region A in the one-wavelength resonator 11, and thehalf-wavelength resonator B in the one-wavelength resonator 11 on astraight line so that the general shape in plan view becomes an I shape.Moreover, a plurality of half-wavelength resonators 10 may be formed inmultiple stages in the waveguide 3.

As shown in FIG. 1, the input line 2 is disposed on a surface on whichthe ground electrode 6 is formed of the dielectric substrate 5 so as toface the ground electrode 7 while sandwiching the dielectric substrate5, thereby constructing a microstrip line. One end side of the inputline 2 is directly connected and conducted to a part corresponding tothe half-wavelength resonator 10 in the ground electrode 6 (in otherwords, a part in which the half-wavelength resonator 10 is constructed).With the configuration, the input line 2 is magnetically coupled to thewaveguide 3 on an E plane (a plane parallel with an electric field) ofthe waveguide 3. In this case, the propagation mode in the waveguide 3is the TE mode and the electromagnetic waves propagate in the Sdirection (that is, the Z direction), so that the E plane of thewaveguide 3 is a plane parallel with an XY plane of FIG. 1.

FIGS. 3 to 5 show magnetic field distributions in the XY cross sectionin and around a connection part between the input line 2 and thewaveguide 3. In this case, a magnetic field H1 in the input line 2 inthe neighborhood of the connection part distributes annularly around theinput line 2 as shown in FIG. 3 since the propagation mode of theelectromagnetic waves is the TEM mode. On the other hand, a magneticfield H2 in the waveguide 3 distributes in one direction in the crosssection as shown in FIG. 4 since the propagation mode of theelectromagnetic waves is the TE mode (TE₁₀ mode). Therefore, as shown inFIG. 5, in the E plane of the waveguide 3 in the connection part, thedirection of the magnetic field H1 in the input line 2 coincides withthat of the magnetic field H2 in the waveguide 3. Consequently, theinput line 2 and the waveguide 3 are magnetically coupled to each other,so that the conversion from the TEM mode to the TE mode is executed.That is, the electromagnetic waves in the TEM mode propagating from theinput line 2 are supplied into the waveguide 3 as the electromagneticwaves in the TE mode.

The pair of output lines 4 a and 4 b is disposed on the surface on whichthe ground electrode 6 is formed in the dielectric substrate 5 so as toface the ground electrode 7 while sandwiching the dielectric substrate 5as shown in FIG. 1, thereby constructing microstrip lines in a mannersimilar to the input line 2. One end sides of the output lines 4 a and 4b are directly connected and conducted to parts corresponding to thehalf-wavelength resonance regions A and B in the one-wavelengthresonator 11 in the ground electrode 6. Concretely, as shown in FIG. 2,when the length of each of the half-wavelength resonance regions A and Bof the one-wavelength resonator 11 is L, the output line 4 a isconnected to the center portion of the half-wavelength resonance regionA (the position apart from the end of the half-wavelength resonanceregion A only by L/2), and the output line 4 b is connected to thecenter portion of the half-wavelength resonance region B (the positionapart from the end of the half-wavelength resonance region B only byL/2). Consequently, in a manner similar to the input line 2, when thedirection of the magnetic field H3 in the half-wavelength resonanceregion A of the one-wavelength resonator 11 coincides with that of amagnetic field H5 in the output line 4 a and the direction of a magneticfield H4 in the half-wavelength resonance region B of the one-wavelengthresonator 11 coincides with that of a magnetic field H6 in the outputline 4 b, the output lines 4 a and 4 b are magnetically coupled to thewaveguide 3 in an E plane (plane parallel with the XY plane in FIG. 1)of the waveguide 3. Therefore, in connection parts between the pair ofoutput lines 4 a and 4 b and the waveguide 3, in a manner opposite tothat in the case of the input line 2, the conversion from the TE mode tothe TEM mode is executed.

Next, the operation of the RF module 1 will be described.

In the RF module 1, electromagnetic waves in the TEM mode supplied tothe input line 2 are supplied as electromagnetic waves in the TE mode tothe half-wavelength resonator 10 and, further, propagate to theone-wavelength resonator 11 via the half-wavelength resonator 10. Inthis case, as schematically shown in FIG. 2, the directions of themagnetic fields H3 and H4 generated in an H plane in the half-wavelengthresonance regions A and B of the one-wavelength resonator 11 (planeparallel with the magnetic field, that is, plane parallel with the XYplane) are always opposite to each other in a frequency band where theone-wavelength resonator 11 acts as a resonator on electromagnetic waves(a signal passband of the RF module 1). Therefore, the directions of themagnetic fields H5 and H6 in the output lines 4 a and 4 b connected tothe half-wavelength resonance regions A and B, respectively, are alsoalways opposite to each other in the signal passband. As a result, thephases of the electromagnetic waves in the TEM mode output from theone-wavelength resonator 11 to the output lines 4 a and 4 b are shiftedfrom each other almost by 180 degrees in the signal passband. Accordingto the result of a simulation, in the RF module 1, as shown in FIG. 6,the phase difference between the electromagnetic waves output from theoutput lines 4 a and 4 b is almost constant in a range from 180 degreesto 190 degrees in a wider frequency band (a band from about 24.5 GHz toabout 26.5 GHz) including the signal passband (a band from about 25 GHzto about 25.4 GHz). Therefore, the electromagnetic waves in the TEM modeconverted to be balanced are output from the pair of output lines 4 aand 4 b. That is, the RF module 1 also functions as an unbalanced tobalanced converter.

On the other hand, as shown in FIG. 7, the intensity distribution of themagnetic field H3 in the E plane to which the output line 4 a in thehalf-wavelength resonance region A is connected is the widest in thecenter portion and becomes narrower toward the ends in the longitudinaldirection (the X or Z direction) of the half-wavelength resonance regionA (in the diagram, the intensity of the magnetic field H3 is expressedby the length of an arrow). In the thickness direction (Y direction) ofthe half-wavelength resonance region A, the intensity distribution ofthe magnetic field H3 in the E plane is almost uniform as shown in FIG.7. The intensity distributions in the half-wavelength resonance region Bare similar to the above and, moreover, the output lines 4 a and 4 b areconnected in almost the same positions in the half-wavelength resonanceregions A and B in the same one-wavelength resonator 11 (portions whichare almost symmetrical to each other with respect to the coupling planeas a center in which the half-wavelength resonance regions A and B arecoupled to each other, that is, the almost center portions in the Xdirection in this example). Consequently, the intensity distributions ofthe magnetic fields H3 and H4 in the E plane to which the output lines 4a and 4 b are connected are almost the same. Therefore, the magneticfields H5 and H6 of the output lines 4 a and 4 b magnetically coupled tothe magnetic fields H3 and H4, respectively, always have also almost thesame intensity in the signal passband where the one-wavelength resonator11 acts as a resonator for electromagnetic waves. As a result, theintensities of the electromagnetic waves in the TEM mode output from theoutput lines 4 a and 4 b via one-wavelength resonator 11 are almost thesame. Therefore, the balanced electromagnetic waves in the TEM modewhose magnitudes are balanced (having the same magnetic field intensity)are output from the pair of output lines 4 a and 4 b. According to theresult of the simulation, in the RF module 1, as shown in FIG. 8, theintensities (attenuation amounts) of the electromagnetic waves outputfrom the pair of output lines 4 a and 4 b almost coincide with eachother in the signal passband. The magnitude balance of the balancedelectromagnetic waves in the TEM mode output from the pair of outputlines 4 a and 4 b can be adjusted by changing the positions ofconnection to the half-wavelength resonance regions A and B of theoutput lines 4 a and 4 b.

As described above, in the RF module 1, the one-wavelength resonator 11is formed on the output side in the waveguide 3 having the area which issurrounded by the pair of ground electrodes 6 and 7 disposed so as toface each other and the plurality of through holes 8 through which thepair of ground electrodes 6 and 7 are conducted to each other, andconstructed so that the electromagnetic waves in the TE mode canpropagate, and the output lines 4 a and 4 b are connected to theportions corresponding to the half-wavelength resonance regions A and Bof the one-wavelength resonator 11 in the ground electrodes 6 as one ofthe pair of ground electrodes 6 and 7. Consequently, the phasedifference between the electromagnetic waves output from the outputlines 4 a and 4 b can be made almost 180 degrees without adjustment.Therefore, while realizing a simple configuration, the RF module 1 canconvert electromagnetic waves in the TE mode propagating through thewaveguide 3 into balanced electromagnetic waves in the TEM mode withoutadjustment and output the electromagnetic waves in the TEM mode.

In the RF module 1, the half-wavelength resonator 10 coupled to theone-wavelength resonator 11 via the coupling windows 12 is formed in thewaveguide 3, and the input line 2 is connected to the portioncorresponding the half-wavelength resonator 10 in the ground electrode 6as one of the ground electrodes. With the configuration, theelectromagnetic waves in the TEM mode input from the input line 2 areconverted into the balanced electromagnetic waves in the TEM mode, andthe balanced electromagnetic waves in the TEM mode can be output fromthe pair of output lines 4 a and 4 b. Therefore, the RF module 1 canfunction as a so-called balun.

The invention is not limited to the embodiment described above. Forexample, although the embodiment of the invention has been described byan example in which the input line 2 and the pair of output lines 4 aand 4 b are formed by microstrip lines, as in an RF module 21 shown inFIG. 9, an input line 22 and a pair of output lines 24 a and 24 b can beformed by coplanar lines. As shown in the diagram, the basicconfiguration of the RF module 21 is almost the same as that of the RFmodule 1 only except for the input line 22 and the pair of output line24 a and 24 b employed in place of the input line 2 and the output lines4 a and 4 b, respectively. In FIG. 9, the same reference numerals aredesignated to the components same as those in the RF module 1. Theuppermost layer is hatched and is shown with thickness omitted.

In the case, the input line 22 is formed so as to face the groundelectrode 7 while sandwiching the dielectric substrate 5 and besurrounded by the ground electrode 6 on the surface on which the groundelectrode 6 is formed in the dielectric substrate 5. One end side of theinput line 22 is directly connected and conducted to a partcorresponding to the half-wavelength resonator 10 in the groundelectrode 6. The ground electrode 6 surrounding the input line 22 isconducted to a facing part in the ground electrode 7 via a plurality ofthrough holes 29 (having the same structure as that of the through holes8 and 9) which penetrate the dielectric substrate 5, are in parallelwith the input line 22, and are provided on both sides of the input line22. With this configuration, the input line 22 functions as a coplanarline. Each of the pair of the output lines 24 a and 24 b is formed in amanner similar to the input line 22 and functions as a coplanar line.

The foregoing embodiment has been described by using the configurationas an example in which the input line 2 and the pair of the output lines4 a and 4 b or the input line 22 and the pair of output lines 24 a and24 b are provided on the surface on which the ground electrode 6 isformed in the dielectric substrate 5 so as to be directly connected tothe ground electrode 6. It is also possible to construct an RF module byusing a dielectric substrate having the ground electrodes 6 and 7 on thetop and under faces and another conductive layer as an intermediateportion between the ground electrodes 6 and 7 and by forming an inputline and a pair of output lines by the conductive layer in theintermediate portion. Referring to FIG. 10, the configuration of aconnection part between an input line and a waveguide of an RF module 31shown in the diagram will be described. In FIG. 10, to facilitateunderstanding of the configuration of the connection part, part of thethrough holes 8 positioned on the front side of through holes 38 whichwill be described later is omitted, and the one-wavelength resonator 11and a pair of output lines are omitted. In the diagram, the conductorlayer D as an intermediate layer is hatched and is shown with thicknessomitted.

In the RF module 31, two dielectric substrates 5 are stacked via theconductor layer D. The ground electrode 6 is formed on the surface ofone of the dielectric substrates 5 (the top face of the dielectricsubstrate 5 on the upper side in FIG. 10), and the other groundelectrode 7 is formed on the surface of the other dielectric substrate 5(the under face of the dielectric substrate 5 on the lower side in FIG.10). The grand electrodes 6 and 7 are conducted to each other throughthe plurality of through holes 8 penetrating the two dielectricsubstrates 5 and the conductor layer D. The conductor layer D surroundedby the plurality of through holes 8 is removed as shown in FIG. 10. As aresult, a waveguide 33 is formed by the ground electrodes 6 and 7 andthe through holes 8. An input line 32 is formed by a strip line by usingthe conductor layer D. As shown in FIGS. 10 and 11, one end side of theinput line 32 is conducted only to the ground electrode 7 via the otherthrough holes 38. The input line 32 is sandwiched by a plurality ofthrough holes 39 through which the ground electrodes 6 and 7 areconducted to each other in a manner similar to the through holes 8 andwhich are provided on both sides of the input line 32. With thisconfiguration, the input line 32 functions as a coplanar line.

In the RF module 31, as shown in FIG. 11, the magnetic field H1 of theinput line 32 through which the electromagnetic waves in the TEM modepropagate is distributed annularly around the input line 32. In thiscase, since the through holes 38 through which the input line 32 isconducted to the ground electrode 7 exist on one end side of the inputline 32, a region in which the through holes 38 do not exist (theupper-side area in FIG. 11) functions as a coupling window 12.Therefore, the direction of the magnetic field H1 in the input line 32on the E plane of the waveguide 33 and that of the magnetic field H2 inthe waveguide 33 coincide with each other. Consequently, the input line32 and the waveguide 33 are magnetically coupled to each other, therebyperforming conversion from the TEM mode to the TE mode. Although it isnot shown, a pair of output lines is also formed in a manner similar tothe input line 32. Electromagnetic waves in the TE mode of theone-wavelength resonator (not shown) formed in the waveguide 33 areconverted into balanced electromagnetic waves in the TEM mode, and theelectromagnetic waves in the TEM mode are output.

In the foregoing embodiments, the RF modules 1, 21, and 31 have beendescribed, which convert electromagnetic waves in the TEM mode inputfrom one input line 2 (22 or 32) into the balanced electromagnetic wavesin the TEM mode and output the balanced electromagnetic waves in the TEMmode from the pair of output lines 4 a and 4 b (or 24 a and 24 b) byforming the one-wavelength resonator 11 on the output side of thewaveguide 3 or 33 and forming the half-wavelength resonator 10 on theinput side. Alternately, like an RF module 41 schematically shown inFIG. 12, a balanced-input to balanced-output type RF module (forexample, a filter) can be also constructed by forming one-wavelengthresonators 42 and 43 on both of the input side and the output side of awaveguide 44. In this case, an input line 44 a is provided in ahalf-wavelength resonance region E of the one-wavelength resonator 42disposed on the input side and the other input line 44 b is provided ina half-wavelength resonance region F of the one-wavelength resonator 42.An output line 45 a is provided in a half-wavelength resonance region Gof the one-wavelength resonator 43 provided on the output side and theother output line 45 b is provided in a half-wavelength resonance regionH of the one-wavelength resonator 43. A coupling window 46 a forcoupling the regions E and G is disposed between the half-wavelengthresonance region E of the one-wavelength resonator 42 and thehalf-wavelength resonance region G of the one-wavelength resonator 43. Acoupling window 46 b for coupling the regions F and H is disposedbetween the half-wavelength resonance region F of the one-wavelengthresonator 42 and the half-wavelength resonance region H of theone-wavelength resonator 43.

In the RF module 41, one electromagnetic wave (magnetic field H41) whichis input to the input line 44 a as one of the input lines of theone-wavelength resonator 42 and forms a balanced electromagnetic wave inthe TEM mode is output as an electromagnetic wave in the TEM mode(magnetic field H47) to the output line 45 a via the half-wavelengthresonance region E (magnetic field H43 in the region) of theone-wavelength resonator 42, the coupling window 46 a, and thehalf-wavelength resonance region G (magnetic field H45 in the region) ofthe one-wavelength resonator 43. On the other hand, the otherelectromagnetic wave (magnetic field H42) which is input to the inputline 44 b of the one-wavelength resonator 42 and forms anelectromagnetic wave in the TEM mode is output as an electromagneticwave in the TEM mode (magnetic field H48) to the output line 45 b viathe half-wavelength resonance region F of the one-wavelength resonator42 (magnetic field H44 in the region), the coupling window 46 b, and thehalf-wavelength resonance region H (magnetic field H46 in the region) ofthe one-wavelength resonator 43. Therefore, the RF module 41 functionsas a balanced-input to balanced-output typed filter.

The RF module 1 in which the half-wavelength resonator 10 is formed onthe input side of the waveguide 3, the one-wavelength resonator 11 isformed on the output side, and the half-wavelength resonator 10 and theone-wavelength resonator 11 are coupled to each other via the couplingwindows 12 has been described as an example. However, the invention isnot limited to the configuration. For example, as shown in FIG. 13, anRF module 1A includes at least one (in the diagram, one as an example)another resonator (a half-wavelength resonator 10A whose basic operationis the same as that of the half-wavelength resonator 10) which is formedbetween the half-wavelength resonator 10 and the one-wavelengthresonator 11 and coupled to both of the resonators 10 and 11 via thecoupling windows 12. The another RF module 21 can be also similarlyconstructed by disposing other resonators (one-wavelength resonator andhalf-wavelength resonator) between the half-wavelength resonator 10 andthe one-wavelength resonator 11 via coupling windows. The adoption ofthe configurations enables the RF module to function as a filter ofvarious frequency characteristics.

The RF module 41 in which the one-wavelength resonators 42 and 43 areformed on the input side and the output side, respectively, of thewaveguide 44 and both of the one-wavelength resonators 42 and 43 aredirectly coupled to each other via the coupling windows 46 a and 46 bhas been described above. However, the invention is not limited to theconfiguration. For example, it is sufficient that the one-wavelengthresonators 42 and 43 are disposed at least on the input side and outputside of the waveguide 44. As shown in FIG. 14, the RF module 41Aincludes at least one (for example, one in the diagram) anotherresonator (in the diagram, as an example, the half-wavelength resonator42A whose basic operation is the same as that of the half-wavelengthresonator 10) which is formed between the one-wavelength resonator 42(another one-wavelength resonator) and the one-wavelength resonator 43and coupled to both of the resonators 42 and 43 via the coupling windows46 a and 46 b. The adoption of this configuration also enables the RFmodule to function as a filter of various frequency characteristics.

In the RF module 1 (or 21) described above, both of the input line 2 (or22) and the pair of the output lines 4 a and 4 b (or 24 a and 24 b) areformed on the surface on which the ground electrode 6 is formed in thedielectric substrate 5. However, the input line 2 (or 22) and the pairof output lines 4 a and 4 b (or 24 a and 24 b) do not always have to beformed on the same surface in the dielectric substrate 5. For example,although it is not shown, another configuration may be employed in whichthe input line 2 (or 22) is formed on the side of the ground electrode 6in the dielectric substrate 5 and the pair of output lines 4 a and 4 b(or 24 a and 24 b) is formed on the side of the ground electrode 7 inthe dielectric substrate 5. A configuration in which the components aredisposed on the opposite sides may be also employed. Further, theembodiments have been described in which one kind out of a strip line, amicrostrip line, and a coplanar line is uniformly used for the inputlines and the output lines. However, it is sufficient to use one kindfor the input lines and another kind for the output lines and therefore,input lines and output lines can be also formed of a mutually differentkind of lines. For example, it is possible to use microstrip lines asthe input lines and use coplanar lines as the pair of output lines.

As described above, the RF module according to the invention includes:the waveguide having the area which is surrounded by the pair of groundelectrodes provided to face each other and the conductors through whichthe pair of ground electrodes are conducted to each other, and in whichelectromagnetic waves in the TE mode can propagate and theone-wavelength resonator is formed; and the pair of output lines whichare connected to portions corresponding to half-wavelength resonanceregions of the one-wavelength resonator in one of the pair of groundelectrodes. Consequently, in the signal passband, the phase differencebetween electromagnetic waves output from the output lines can be set toalmost 180 degrees without adjustment. As a result, the RF module doesnot require the adjustment between a capacitance value of capacitativecoupling and an inductance value of inductive coupling while realizing asimpler configuration in comparison with RF modules of the related art.Since the adjustment work can be made unnecessary and it is notnecessary to provide a signal path which is not operated as a resonatorin addition to the resonator, the RF module can be sufficientlyminiaturized. By constructing the pair of output lines so thatelectromagnetic waves in the TEM mode can propagate, adjustment isunnecessary and balanced electromagnetic waves in the TEM mode can beoutput from the pair of output lines.

The RF module according to the invention includes the half-wavelengthresonator formed inside the waveguide and coupled to the one-wavelengthresonator, and the input line which is connected to the portioncorresponding to the half-wavelength resonator in one of the pair ofground electrodes and through which electromagnetic waves in the TEMmode can be input as electromagnetic waves in the TE mode to thehalf-wavelength resonator. Consequently, the electromagnetic waves inthe TEM mode input from the input line can be converted into balancedelectromagnetic waves in the TEM mode, and the balanced electromagneticwaves in the TEM mode can be output from the pair of output lines. Thatis, the RF module can function as a so-called balun. In this case, thehalf-wavelength resonator and the one-wavelength resonator can becoupled to each other via the coupling window.

The RF module according to the invention includes, between thehalf-wavelength resonator and the one-wavelength resonator, at least oneanother resonator coupled to both of the resonators via the couplingwindow. Consequently, the RF module which can function as a filter ofvarious frequency characteristics can be provided.

The RF module according to the invention includes another one-wavelengthresonator formed inside the waveguide and coupled the one-wavelengthresonator, and the pair of input lines which are connected to theportions corresponding to the half-wavelength resonance regions of theother one-wavelength resonator in one of the pair of ground electrodesand through which the electromagnetic waves in the TEM mode can be inputas the electromagnetic waves in the TE mode to the other one-wavelengthresonator. Consequently, the balanced electromagnetic waves in the TEMmode can be output as the balanced electromagnetic waves in the TEMmode. In this case, the other one-wavelength resonator and theone-wavelength resonator can be coupled to each other via the couplingwindow.

The RF module according to the invention includes, between the otherone-wavelength resonator and the one-wavelength resonator, at least oneanother resonator which is coupled to both of the resonators via thecoupling window. Consequently, the RF module which can function as afilter of various frequency characteristics can be provided.

1. An RF module comprising: a waveguide having an area which issurrounded by a pair of ground electrodes and a conductor for makingelectrical connection between the pair of ground electrodes, the pair ofground electrodes being provided so as to face each other, and in whichelectromagnetic waves in the TE mode can propagate and a one-wavelengthresonator is formed; and a pair of output lines connected to portionscorresponding to half-wavelength resonance regions of the one-wavelengthresonator in one of the pair of ground electrodes.
 2. The RF moduleaccording to claim 1, wherein the pair of output lines is formed so thatelectromagnetic waves in the TEM mode can propagate.
 3. The RF moduleaccording to claim 1, comprising: a half-wavelength resonator formedinside the waveguide and coupled to the one-wavelength resonator; and aninput line which is connected to a portion corresponding to thehalf-wavelength resonator in one of the pair of ground electrodes andthrough which electromagnetic waves in the TEM can be input aselectromagnetic waves in the TE mode to the half-wavelength resonator.4. The RF module according to claim 3, wherein the half-wavelengthresonator and the one-wavelength resonator are coupled to each other viaa coupling window.
 5. The RF module according to claim 3, furthercomprising at least one another resonator which is formed between thehalf-wavelength resonator and the one-wavelength resonator and coupledto both of the resonators via a coupling window.
 6. The RF moduleaccording to claim 1, further comprising: another one-wavelengthresonator formed inside the waveguide and coupled to the one-wavelengthresonator; and a pair of input lines which are connected to portionscorresponding to half-wavelength resonance regions of the anotherone-wavelength resonator in one of the pair of ground electrodes andthrough which electromagnetic waves in the TEM mode can be input aselectromagnetic waves in the TE mode to the another one-wavelengthresonator.
 7. The RF module according to claim 6, wherein the anotherone-wavelength resonator and the one-wavelength resonator are coupled toeach other via a coupling window.
 8. The RF module according to claim 6,further comprising at least one resonator formed between the anotherone-wavelength resonator and the one-wavelength resonator and coupled toboth of the resonators via a coupling window.
 9. The RF module accordingto claim 3, wherein the input line is any one of a strip line, amicrostrip line, and a coplanar line.
 10. The RF module according toclaim 1, wherein the output line is any one of a strip line, amicrostrip line, and a coplanar line.